rcs380.py: TypeError: format() argument after * must be a sequence, not NoneType

Hello,

We’ve been using nfcpy on an Intel Edison with a USB-plugged Sony RC-S380 for quite some time now. We are spawning the examples/tagpool.py script from our program like this:

python examples/tagpool.py -l

Then we listen to it’s output and from then we get the value of the scanned ID card. It works very fine, but sometimes the process crashes with the following error:

nfcpy/nfc/clf/rcs380.py", line 307, in get_firmware_version
   log.debug("firmware version {1:x}.{0:02x}".format(*data))
TypeError: format() argument after * must be a sequence, not NoneType

I was not able to reproduce this problem. However, it happens regularly on our production devices (and seemingly randomly), often enough so that we are worrying about it.

Does anyone have any idea where does this come from and how to fix it? Thanks.

[nehpetsde]

The log was quite helpful as it shows that the reader itself is still responsive but returns the response for an older command. This would not happen if nfcpy terminates gracefully but may easily happen if unfriendly killed. I’d guess you’re using the kill methodology as part of your application logic. That you only see it happen sparsely is most likely due to the speed of the Edison, on my workstation PC is’s more or less immediate.

Fortunately the chip logic is stable enough to allow to fix this by removing any leftover response data during initialization. With your the shell script kill loop it’s now running since two hours.

[malikolivier]

As ugly as it may seem, we can still use the NFC reader and read data from it even when the above issue occurs, as this patch shows: https://github.com/nfcpy/nfcpy/compare/master...malikolivier:dirty-fix?expand=1

EDIT: It worked at some point of this day, but does not work anymore, you can see the errors log there. I do not know if this helps. Anyway, seems like the PC cannot read anything from the device.

https://gist.github.com/malikolivier/50f54cf26b70164a62cece1ef8ae6598